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full Contents for  TS 23.503  Word version:   16.4.1

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6.2  Network functions and entities
6.2.1  Policy Control Function (PCF)
6.2.1.1  General
The PCF provides the following session management related functionality:
  • Policy and charging control for a service data flows;
  • PDU Session related policy control;
  • PDU Session event reporting to the AF.
The PCF provides authorized QoS for a service data flow.
The PCF uses the service information received from the AF (e.g. SDP information or other available application information) and/or the subscription information received from the UDR to calculate the proper QoS authorization (QoS class identifier, bitrates). The PCF may also take into account the requested QoS received from the SMF via N7 interface and the Analytics related to "Service Experience" received by NWDAF.
NOTE 1:
The PCF provides always the maximum values for the authorized QoS even if the requested QoS is lower than what can be authorized.
The Authorization of QoS resources shall be based on complete service information unless the PCF is required to perform the authorization of QoS resources based on incomplete service information. The PCF shall after receiving the complete service information, update the affected PCC rules accordingly.
At reception of the service information from the AF if configured through policy and taking into account information defined in TS 26.114, the PCF determines the Maximum Packet Loss Rate for UL and DL based on the service information and sends it to SMF along with the PCC rule.
NOTE 2:
Based on local configuration, the PCF sets the Maximum Packet Loss Rate (UL, DL) corresponding to either the most robust codec configuration (e.g., codec, mode, redundancy) or the least robust codec configuration of the negotiated set in each direction.
NOTE 3:
Details for setting the Maximum Packet Loss Rate are specified by SA4.
The PCF supports usage monitoring control for a PDU Session or per Monitoring Key.
The PCF may receive information about total allowed usage per DNN and S-NSSAI combination and UE from the UDR, i.e. the overall amount of allowed resources (based either on traffic volume and/or traffic time) that are to be monitored for the PDN connections of a user. In addition, information about total allowed usage for Monitoring key(s) per DNN and S-NSSAI combination and UE may also be received from the UDR. For the purpose of usage monitoring per access type, the PCF receives an individual Monitoring key per access type from UDR.
For the purpose of usage monitoring control the PCF shall request the Usage report trigger and provide the necessary usage threshold(s), either volume threshold, time threshold, or both volume threshold and time threshold, upon which the requested node (SMF) shall report to the PCF. The PCF shall decide if and when to activate usage monitoring to the SMF.
The PCF may provide a Monitoring time to the SMF for the Monitoring keys(s) and optionally specify a subsequent threshold value for the usage after the Monitoring time.
If the SMF reports usage before the Monitoring time is reached, the Monitoring time is not retained by the SMF. Therefore, the PCF may again provide a Monitoring time and optionally the subsequent threshold value for the usage after the Monitoring time in the response.
It shall be possible for the PCF to request a usage report from the requested node (SMF).
NOTE 4:
The PCF ensures that the number of requests/following policy decisions provided over N7 reference point do not cause excessive signalling load by e.g. assigning the same time for the report only for a preconfigured number of PDU sessions.
Once the PCF receives a usage report from the requested node (SMF) the PCF shall deduct the value of the usage report from the totally allowed usage for that DNN and S-NSSAI combination and UE (if usage per PDU session is reported). If usage is reported from the SMF, the PCF shall deduct the value of the usage report from the totally allowed usage for individual Monitoring key(s) for that DNN and S-NSSAI combination and UE (if usage for one or several Monitoring keys is reported).
NOTE 5:
The PCF maintains usage thresholds for each Monitoring key and PDU session that is active for a certain DNN and S-NSSAI combination and UE. Updating the total allowanced usage after the SMF reporting, minimizes the risk of exceeding the usage allowance.
If the SMF reports usage for a certain Monitoring key and if monitoring shall continue for that Monitoring key then the PCF shall provide new threshold value(s) in the response to the SMF respectively. If Monitoring time and subsequent threshold value are used then the PCF provides them to the SMF as well.
The PCF may provide a new volume threshold and/or a new time threshold to the SMF, the new threshold values overrides the existing threshold values in the SMF.
If monitoring shall no longer continue for that Monitoring key, then the PCF shall not provide a new threshold in the response to the SMF.
If all PDU session of a user to the same DNN and S-NSSAI combination is terminated, the PCF shall store the remaining allowed usage, i.e. the information about the remaining overall amount of resources, in the UDR.
The PCF may authorise an application service provider to request specific PCC decisions (e.g. authorisation to request sponsored IP flows, authorisation to request QoS resources) based on sponsored data connectivity profile from the UDR. For sponsored data connectivity, the PCF may receive a usage threshold from the AF. If the AF specifies a usage threshold, the PCF shall use the Sponsor Identity to construct a Monitoring key for monitoring the volume, time, or both volume and time of user plane traffic, and invoke usage monitoring on the SMF. The PCF shall notify the AF when the SMF reports that a usage threshold for the Monitoring key is reached provided that the AF requests to be notified for this event, as described in clause 6.1.3.18. If the usage threshold is reached, the AF may terminate the AF session or provide a new usage threshold to the PCF. Alternatively, the AF may allow the session to continue without specifying a usage threshold. If the AF decides to allow the session to continue without specifying a usage threshold, then monitoring in the SMF shall be discontinued for that monitoring key by the PCF, unless there are other reasons for continuing the monitoring.
If the H-PCF detects that the UE is accessing the sponsored data connectivity in the roaming scenario with home routed access, it may allow the sponsored data connectivity in the service authorization request, reject the service authorization request, or initiate the AF session termination based on home operator policy.
NOTE 6:
Sponsored data connectivity is not supported in the roaming with visited access scenario in this Release.
If the AF revokes the service information and the AF has notified previously a usage threshold to the PCF, the PCF shall report the usage up to the time of the revocation of service authorization.
If the PDU session terminates and the AF has specified a usage threshold then the PCF shall notify the AF of the accumulated usage (i.e. either volume, or time, or both volume and time) of user plane traffic since the last usage report.
The PCF reports PDU Session events, e.g. Access Type, RAT Type (if applicable), Access Network Information, PLMN identifier where the UE is located, as described in clause 6.1.3.18.
The subscription and reporting of events when the target for reporting is an Internal Group Identifier or any UE accessing a combination of (DNN, S-NSSAI), is described in clause 5.2.5.7 of TS 23.502. The events that can be reported by the PCF are described in clause 6.1.3.18.
The subscription and reporting of events targeting an individual UE IP address (IPv4 address or IPv6 prefix) and optionally the DN information are described below. The events that can be reported by the PCF are described in clause 6.1.3.18.
The PCF may ensure that the sum of the packet filters used by all PCC rules which trigger the generation of signalled QoS rules does not exceed the number of supported packet filters for signalled QoS rules indicated by the UE for the PDU Session (as defined in clause 5.7.5.1 of TS 23.501).
For EPC IWK, when PCF receives from the SMF of the report on UE resumed from suspend state, the PCF may provision PCC Rules to the SMF to trigger an IP-CAN Session modification procedure.
The PCF may provide the IP index as the PDU session related policy to the SMF for IP address/Prefix allocation at SM Policy Association Establishment. If PCF receives from the SMF an allocated IP address/Prefix for the PDU session, it shall not include IP Index into the PDU session related policy. The PCF provides the following non-session management related functionality:
  • Access and mobility related policy control (as described in clause 6.1.2.1);
  • UE access selection and PDU Session selection related policy control (as described in clause 6.1.2.2);
  • Negotiation for future background data transfer (as described in clause 6.1.2.4).
On receiving the DN Authorization Profile Index provided by the SMF at the establishment or modification of the SM Policy Association for a PDU session, the PCF takes the DN Authorization Profile Index as input for a policy decision and then obtains the list of PCC Rules (as defined in clause 6.3) and/or PDU Session related policy (as defined in clause 6.4) and provides them to the SMF as part of the Session Management Policy Control Data for enforcement.
On receiving the Session AMBR provided by the SMF at the establishment or modification of the SM Policy Association for a PDU session under the conditions defined in TS 23.501, clause 5.6.6, the PCF provides the Authorized Session AMBR as part of the PDU session policy control information defined in clause 6.4.
The PCF provides DNAI(s) in the PCC rule(s) to the SMF, taking into account the AF request and the Local routing indication from the PDU Session policy control subscription information.
When the PCF detects that all PCC rules related to an AF session are removed, or the PCF detects that the SM Policy Association is terminated, the PCF shall request the AF to terminate the AF session. If the SMF indicated that the PCC rules were removed or that the SM Policy Association is terminated due to PS to CS handover, the PCF shall indicate PS to CS handover as cause within the request to terminate the AF session.
NOTE 7:
For 5G-SRVCC (i.e. SRVCC from NG-RAN to UTRAN) as specified in TS 23.216), the SM Policy Association is terminated by the SMF. For SRVCC (i.e. SRVCC from E-UTRAN to GERAN/UTRAN) as specified in TS 23.216, the SMF indicates that PCC rules are removed.
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6.2.1.2  Input for PCC decisionsWord-p. 61
The PCF shall accept input for PCC decision-making from the SMF, the AMF, the CHF, the NWDAF if present, the UDR and if the AF is involved, from the AF, as well as the PCF may use its own predefined information. These different nodes should provide as much information as possible to the PCF. At the same time, the information below describes examples of the information provided. Depending on the particular scenario all the information may not be available or is already provided to the PCF.
The AMF may provide the following information:
  • SUPI;
  • The PEI of the UE;
  • Location of the subscriber;
  • Service Area Restrictions;
  • RFSP Index;
  • RAT Type;
  • GPSI;
  • Access Type;
  • Serving Network identifier (PLMN ID or PLMN ID and NID, see clause 5.34 of TS 23.501);
  • Allowed NSSAI;
  • UE time zone;
  • Subscribed UE-AMBR;
  • Mapping Of Allowed NSSAI;
  • S-NSSAI for the PDU Session;
  • Requested DNN.
NOTE 1:
The Access Type and RAT Type parameters should allow extension to include new types of accesses.
The UE may provide the following information:
  • OSId;
  • List of PSIs;
  • Indication of UE support for ANDSP.
The SMF may provide the following information:
  • SUPI;
  • The PEI of the UE;
  • IPv4 address of the UE;
  • IPv6 network prefix assigned to the UE;
  • Default 5QI and default ARP;
  • Request type (initial, modification, etc.);
  • Type of PDU Session (IPv4, IPv6, IPv4v6, Ethernet, Unstructured);
  • Access Type;
  • RAT Type;
  • GPSI;
  • Internal-Group Identifier
  • Location of the subscriber;
  • S-NSSAI;
  • NSI-ID (if available);
  • DNN;
  • Serving Network identifier (PLMN ID or PLMN ID and NID, see clause 5.34 of TS 23.501);
  • Application identifier;
  • Allocated application instance identifier;
  • Detected service data flow descriptions;
  • UE support of reflective QoS (as defined in clause 5.7.5.1 of TS 23.501);
  • Number of supported packet filters for signalled QoS rules (indicated by the UE as defined in clause 5.7.5.1 of TS 23.501);
  • 3GPP PS Data Off status;
  • DN Authorization Profile Index (see clause 5.6.6 of TS 23.501);
  • Session AMBR (see clause 5.6.6 of TS 23.501).
The UDR may provide the information for a subscriber connecting to a specific DNN and S-NSSAI, as described in the sub clause 6.2.1.3.
The UDR may provide the following policy information related to an ASP:
  • The ASP identifier;
  • A transfer policy together with a Background Data Transfer Reference ID, the volume of data to be transferred per UE, the expected amount of UEs.
NOTE 2:
The information related with AF influence on traffic routing may be provided by UDR when the UDR serving the NEF is deployed and stores the application request.
The AF, if involved, may provide the following application session related information directly or via NEF, e.g. based on SIP and SDP:
  • Subscriber Identifier;
  • IP address of the UE;
  • Media Type;
  • Media Format, e.g. media format sub-field of the media announcement and all other parameter information (a= lines) associated with the media format;
  • Bandwidth;
  • Sponsored data connectivity information;
  • Flow description, e.g. source and destination IP address and port numbers and the protocol;
  • AF application identifier;
  • AF-Service-Identifier, or alternatively, DNN and possibly S-NSSAI
  • AF Communication Service Identifier (e.g. IMS Communication Service Identifier), UE provided via AF;
  • AF Application Event Identifier;
  • AF Record Information;
  • Flow status (for gating decision);
  • Priority indicator, which may be used by the PCF to guarantee service for an application session of a higher relative priority;
  • NOTE 3:
    The AF Priority information represents session/application priority and is separate from the MPS 5GS Priority indicator.
  • Emergency indicator;
  • Application service provider;
  • DNAI;
  • Information about the N6 traffic routing requirements;
  • GPSI;
  • Internal-Group Identifier;
  • Temporal validity condition;
  • Spatial validity condition;
  • AF subscription for early and/or late notifications about UP management events;
  • AF transaction identifier;
  • TSN QoS information as described in clause 6.1.3.23.
  • QoS information to be monitored;
  • Reporting frequency.
The AF may provide the following background data transfer related information via NEF:
  • Background Data Transfer Reference ID.
  • Background Data Transfer Policy.
  • Volume per UE.
  • Number of UEs.
  • Desired time window.
  • Network Area Information.
The CHF, if involved, may provide the following information for a subscriber:
  • Policy counter status for each relevant policy counter.
The NWDAF, if involved, may provide analytics information as described in clause 6.1.1.3.
In addition, the predefined information in the PCF may contain additional rules based on charging policies in the network, whether the subscriber is in its home network or roaming, depending on the QoS Flow attributes.
The 5QIs (see clause 5.7.4 of TS 23.501) in the PCC rule is derived by the PCF from AF or UDR interaction if available. The input can be SDP information or other available application information, in line with operator policy.
The Allocation and Retention Priority in the PCC Rule is derived by the PCF from AF or UDR interaction if available, in line with operator policy.
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6.2.1.3  Policy control subscription information managementWord-p. 65
The PCF may request subscription information at PDU Session establishment and during the UE Policy Association Establishment procedure.
The PCF may receive notifications on changes in the subscription information. Upon reception of a notification, the PCF shall make the policy control decisions necessary to accommodate the change in the subscription and shall update the SMF and/or the AMF if needed.
NOTE 1:
How the PCF provisions/retrieves information related with policy control subscription data is defined in TS 23.501.
The policy control subscription profile information provided by the UDR during the UE Policy Association Establishment procedure using Nudr service for Data Set "Policy Data" and Data Subset "UE context policy control data" is described in Table 6.2-1:
Information name
Description
Category

Subscriber categories
List of category identifiers associated with the subscriber
Optional
Tracing Requirements
Tracing requirements as defined in TS 32.421
Optional
PEI
The Permanent Equipment Identifier of the UE.
Optional
OSId
Identifies the operating system supported by UE.
Optional
Indication of UE support for ANDSP
Indicates the UE support for ANDSP.
Optional
S-NSSAI subscription information
Contains the list of subscribed S-NSSAIs, its associated subscribed DNNs. For each DNN, the Allowed PDU session types and the Allowed SSC modes.
Optional

NOTE 2:
S-NSSAI subscription information can be part of UE context policy control subscription information and Session Management Subscription data/Slice Selection Subscription data. UDR implementation and the provisioning system are responsible for keeping the consistency of this information when both Data Sets are stored in the same UDR. The provisioning system is responsible for keeping the consistency of this information when both Data Sets are stored in different UDRs.
The policy control subscription profile information provided by the UDR at PDU Session establishment, using Nudr service for Data Set "Policy Data" and Data Subset "PDU Session policy control data" is described in Table 6.2-2.
Information name
Description
Category

Allowed services
List of subscriber's allowed service identifiers
Optional
Subscriber categories
List of category identifiers associated with the subscriber
Optional
Subscribed GBR
Maximum aggregate bitrate that can be provided across all GBR QoS Flows for the DNN and S-NSSAI.
Optional
ADC support
Indicates whether application detection and control can be enabled for a subscriber
Optional
Subscriber spending limits control
Indicates whether the PCF must enforce policies based on subscriber spending limits
Optional
IP index information
Information that identifies the IP Address allocation method during PDU Session establishment
Optional
Background Data Transfer Reference ID(s)
Reference ID(s) for Background Data Transfer Policies that apply to the UE.
Optional
Local routing indication
Indication on whether AF influence on traffic routing is allowed or not allowed
Optional

Charging related information
This part defines the charging related information in the policy control subscription profile
Default charging method
Default charging method for the PDU Session (online / offline)
Optional
CHF address
The address of the Charging Function and optionally the associated CHF instance ID and CHF set ID (see clause 6.3.1.0 of TS 23.501)
Optional

Usage monitoring related information
This part includes a list of usage monitoring profiles associated with the subscriber. Each usage monitoring profile is logically associated with a particular operator offer, and includes the following elements
Monitoring key
An identifier to a usage monitoring control instance that includes one or more PCC rules
Conditional (NOTE 1)
Usage monitoring level
Indicates the scope of the usage monitoring instance (PDU Session level or per Service)
Optional
Start date
Start date and time when the usage monitoring profile applies
Optional
End date
End date and time when the usage monitoring profile applies
Optional
Volume limit
Maximum allowed traffic volume
Optional
Time limit
Maximum allowed resource time usage
Optional
Reset period
Time period to reset the remaining allowed consumed usage for periodic usage monitoring control (postpaid subscriptions)
Optional

MPS subscription data
This part defines the MPS subscription information in the policy control subscription profile
MPS priority
Indicates subscription to MPS priority service; priority applies to all traffic on the PDU Session
Conditional (NOTE 1)
IMS signalling priority
Indicates subscription to IMS signalling priority service; priority only applies to IMS signalling traffic
Conditional (NOTE 1)
MPS priority level
Relative priority level for multimedia priority services
Conditional (NOTE 1)
MCS priority
Indicates subscription to MCS priority service; priority applies to all traffic on the PDU Session
Conditional (NOTE 1)
MCS priority level
Relative priority level for MCS services
Conditional (NOTE 1)

NOTE 1:
The information is mandatory if the specific part is included in the subscription information (e.g. the monitoring key is mandatory if the usage monitoring information part is included)

Information name
Description
Category

Remaining allowed usage related information
This part includes a list of Remaining allowed usage associated with the subscriber.
Monitoring key
An identifier to a usage monitoring control included one or more PCC rules
Conditional (NOTE 1)
Usage monitoring level
Iindicates the scope of the usage monitoring (PDU Session level or service level)
Optional
Volume usage
Remaining allowed traffic volume
Optional
Time usage
Remaining allowed resource time usage
Optional

NOTE 1:
The information is mandatory if the specific part is included in the subscription information (e.g. the monitoring key is mandatory if the usage monitoring information part is included)

The Allowed services may comprise any number of service identifiers allowed for the subscriber in the PDU Session. The PCF maps those service identifiers into PCC rules according to local configuration and operator policies.
The Subscriber category may comprise any number of identifiers associated with the subscriber (e.g. gold, silver, etc.). Each identifier associates operator defined policies to the subscriber that belong to that category.
The Usage monitoring related information may comprise any number of usage monitoring control instances associated with the subscriber. In each usage monitoring control instance is mandatory to include the Monitoring key. The Reset period only applies to usage monitoring control instances that periodically reset the allowed usage (e.g. daily, monthly, etc.). If the Reset period is not specified, the usage monitoring control instance ends when the allowed data is consumed or when the End date is reached. The usage monitoring related information is used by the PCF instead of the respective information for the subscriber category.
The policy subscription profile may be extended with operator-specific information. Operator-specific extensions may be added both to any specific part of the policy control subscription information (e.g. to the subscriber category part), or as a new optional information block.
Handling of operator specific policy data by the PCF is out of scope of this specification in this release.
The policy control subscription profile information provided by the UDR during the UE Policy Association Establishment procedure using Nudr service for Data Set "Policy Data" and Data Subset "Policy Set Entry" is described in Table 6.2-4.
Information name
Description
Category

Policy Set Entry
List of PSIs and content for each PSI. Content may be Access Network Discovery & Selection Policy Information or UE Route Selection Policy information or both.
Optional

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6.2.1.4  V-PCFWord-p. 67
The V-PCF is a functional element that encompasses policy control decision functionalities in the VPLMN.
For SM-related policy control, the V-PCF only includes functionality for local breakout roaming scenario based on roaming agreements.
For UE policy control, the V-PCF receives the UE policy from the H-PCF and forwards it to the UE via the AMF. The V-PCF can send additional UE policy information (i.e. ANDSP policies) to the UE which is different from the one from H-PCF.
For Access and mobility related policy control, the V-PCF generates the values for RFSP Index, UE-AMBR, Service Area Restriction and SMF selection management.
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6.2.1.5  H-PCF
The H-PCF is a functional element that encompasses policy control decision functionalities in the HPLMN.
For SM-related policy control, the H-PCF only includes functionality for home routed roaming scenario and provides the same functionality as the PCF in the non-roaming case.
For UE policy control, H-PCF generates the UE policy based on subscription data and transfers the UE policy to the UE via the AMF, or via the V-PCF in the roaming case.
6.2.1.6  Application specific policy information managementWord-p. 68
The application specific information used for policy control includes:
  • Negotiation of background data transfer information stored in the UDR as Data Set "Policy Data" and Data Subset "Background Data Transfer data": It contains an ASP identifier, a transfer policy together with the Background Data Transfer Reference ID, the volume of data to be transferred per UE, the expected amount of UEs and optionally, the subscription to notifications when the BDT policy needs to renegotiated;
  • Sponsored data connectivity profile information stored in the UDR as Data Set "Policy Data" and Data Subset "Sponsored data connectivity profile data": It contains a list of ASP identifiers and their applications per sponsor identity;
  • Application Function request information for multiple UEs (per group of UEs or all UEs) stored in the UDR as Data Set "Application Data" and Data Subset "AF request information for multiple UEs".
The application specific policy information may be requested/updated by the PCF per AF request.
The management of Application Function request information for multiple UEs is defined in clause 6.3.7.2 of TS 23.501, the management of policies for the negotiation of background data transfer is defined in clause 6.1.2.4 of this specification and the provision and usage of sponsored data connectivity profile is defined in clause 6.2.1.1 of this specification.
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